沙漠生物结皮高产胞外多糖菌株的筛选与鉴定

摘要

Twenty-seven stains producing exopolysaccharides were isolated from biological soil crusts in the Gurbantunggut Desert,Xinjiang by the traditional method.A strain with 7445.80 mg/L exopolysaccharide-producing activity was picked out of them by phenol-sulfuric acid method and named as XJ-27.Based on phenotypic and physiological-chemical characterization,XJ-27 was primarily identified as Bacillus thuringiensis and further confirmed through 16S rDNA sequence analysis,resulting in a 1452 bp PCR amplification sequence,homology comparison with NCBI databases using the software Blast and phylogenetic tree construction using the software MEGA 4.0.%采用传统的分离纯化方法从沙漠生物结皮中分离到27株产胞外多糖菌株,并通过苯酚-硫酸法从中复筛,筛选到一株产多糖量为7445.80mg/L的菌株XJ-27。根据菌株的形态学特征、生理生化鉴定方法初步鉴定为苏云金芽孢杆菌（Bacillus thuringiensis）;通过16S rDNA基因序列分析对该菌株进行了鉴定,PCR扩增得到1452bp的序列,PCR产物序列通过Blast软件在NCBI网站中进行同源性比较,通过MEGA4.0软件绘制系统发育树,结果进一步确认了该菌的地位,XJ-27在细菌系统发育分类学上也归属为苏云金芽孢杆菌。